Transform matrix to adjacency list
Last updated: August 3, 2025
Quick Overview
Given a matrix representation of a graph, where each element indicates the presence of an edge between nodes, transform this matrix into an adjacency list format. The input will be a 2D array of integers, and the output should be a list of lists, where each sublist contains the adjacent nodes for each node in the graph. Ensure that the solution handles both directed and undirected graphs appropriately.
Goldman Sachs
August 3, 202527
3
1,163 solved
Given a matrix representation of a graph, where each element indicates the presence of an edge between nodes, transform this matrix into an adjacency list format. The input will be a 2D array of integers, and the output should be a list of lists, where each sublist contains the adjacent nodes for each node in the graph. Ensure that the solution handles both directed and undirected graphs appropriately.
This coding problem is frequently asked during Take-home Project at Goldman Sachs. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Goldman Sachs expects candidates to write production-quality code, not just solve the puzzle.
What the Interviewer Expects
- Recognize the underlying problem pattern (sliding window, two pointers, BFS/DFS, etc.)
- Discuss multiple approaches and trade-offs before coding
- Implement an optimal solution with clean, production-quality code
- Handle all edge cases including boundary conditions and invalid input
- Optimize both time and space complexity with clear justification
- Test your solution systematically with well-chosen examples
Key Topics to Cover
How to Approach This
- Clarify input constraints and edge cases before writing code.
- Walk through your approach verbally and confirm with the interviewer before coding.
- Start with a brute force solution, then optimize. Mention time and space complexity.
- Test your solution with examples, including edge cases like empty input or duplicates.
- Consider common patterns: sliding window, two pointers, hash map, BFS/DFS, dynamic programming.
Possible Follow-up Questions
- Can you solve this in a single pass?
- How would you test this solution thoroughly?
- How would you parallelize this solution?
- What happens if the input contains duplicates?
Sharpen Your Skills on Codemia
Practice similar problems with our interactive workspace, get AI feedback, and track your progress.
Practice DSA ProblemsSample Answer
Problem Analysis
The problem requires us to transform a matrix representation of a graph into an adjacency list format. Each cell in the matrix indicates the presence of an edge between nodes, where a value of 1 sig...
Approach
- Initialize an empty adjacency list: Create a list of empty lists where each index corresponds to a node in the graph.
- Iterate through the matrix: Use nested loops to traverse the matrix....
Submit Your Answer
